Blame SOURCES/glibc-sw28537-2.patch
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From 56212a35fe258f45f242f4bb80866e4980e4ec0e Mon Sep 17 00:00:00 2001
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From: "H.J. Lu" <hjl.tools@gmail.com>
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Date: Thu, 11 Nov 2021 06:54:01 -0800
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Subject: [PATCH] Avoid extra load with CAS in __pthread_mutex_clocklock_common
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[BZ #28537]
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Replace boolean CAS with value CAS to avoid the extra load.
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Reviewed-by: Szabolcs Nagy <szabolcs.nagy@arm.com>
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(cherry picked from commit 49302b8fdf9103b6fc0a398678668a22fa19574c)
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---
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nptl/pthread_mutex_timedlock.c | 10 +++++-----
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1 file changed, 5 insertions(+), 5 deletions(-)
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diff --git a/nptl/pthread_mutex_timedlock.c b/nptl/pthread_mutex_timedlock.c
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index 888c12fe..c4627ef6 100644
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--- a/nptl/pthread_mutex_timedlock.c
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+++ b/nptl/pthread_mutex_timedlock.c
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@@ -269,12 +269,12 @@ __pthread_mutex_timedlock (pthread_mutex_t *mutex,
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meantime. */
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if ((oldval & FUTEX_WAITERS) == 0)
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{
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- if (atomic_compare_and_exchange_bool_acq (&mutex->__data.__lock,
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- oldval | FUTEX_WAITERS,
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- oldval)
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- != 0)
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+ int val;
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+ if ((val = atomic_compare_and_exchange_val_acq
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+ (&mutex->__data.__lock, oldval | FUTEX_WAITERS,
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+ oldval)) != oldval)
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{
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- oldval = mutex->__data.__lock;
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+ oldval = val;
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continue;
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}
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oldval |= FUTEX_WAITERS;
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--
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GitLab
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